The very small has been the realm of 8-bit microcontrollers. But Texas Instruments is pushing its MSP430 line where it has never gone before. The 16-bit MSP430F20xx microcontroller is available in a range of packages, including a 14-pin, 4- by 4-mm QFN chip. It's also available in TSSOP and PDIP packages.
The MSP430F20xx family is a major upgrade from the MSP430F1xxx product line. The new siblings are smaller, faster, and more power-efficient at 200 µA/MIPS. The 10 I/O pins have pull-up, pull-down, and interrupt support.
With lower pin counts, these parts benefit from the on-chip 16-MHz clock (see the figure). The single-cycle operation delivers 16 MIPS without cache. The chips have up to 2 kbytes of flash memory and 128 bytes of RAM. There's enough memory to run a small operating system. Its in system programming (ISP) operates down to 2.2 V.
Texas Instruments' 14-pin version of the MSP430F20xx is available with a range of analog peripherals, starting with simple comparators and graduating to an eight-channel, 16-bit sigma-delta analog-to-digital converter (ADC). This version supports differential inputs, including an internal reference and temperature sensor. It can deliver up to 4.096 ksamples/s as well.
The 10-bit sequence and repeat (SAR) ADC is even more interesting. It uses the Direct Transfer Controller (DTC), which moves acquired data directly into memory without processor intervention. The DTC can automatically cycle through inputs. The throughput exceeds 200 ksamples/s.
The Universal Serial Interface (USI) is more than just a serial port. It's designed to handle SPI and I2C protocols. Additionally, it handles I2C start/stop bits. The 16-bit data register can shift out the most or least significant bit first. Any number of bits can be delivered, not just 8 or 16. The new architecture reduces SPI overhead from 425 cycles/transfer to just 10. An efficient serial interface turns networking smart devices into a trivial exercise.
The chips also include the typical timers and power-detection support, making them ideal for controlling the startup of higher-power devices like DSPs. The chips' brownout reset (BOR) requires no external power.
Developers will really appreciate the pin Spy Bi-Wire that provides all the features of a full JTAG interface. There are two hardware breakpoint registers, too.
Pricing for the MSP430F20xx starts at $0.65.